The US secretary of state, Colin Powell, flew into Israel last night with an ominous warning to the prime minister, Ariel Sharon, that the Israeli offensive in the West Bank will not end the suicide bombings.

"No matter how effective the Israeli defence force believes they are being right now ... when it is over there will still be people who are willing to resort to violence and terror, people who are willing to use suicide bombs," he said."That violence and the anger and frustration that fuels it will still be there."

Mr Powell said he spoke to Mr Sharon on the phone from Madrid yesterday morning and the Israeli prime minister had said he was pulling out of two towns and 22 villages. But Mr Powell also noted that "other actions were going on".

Mohammed Dahlan, head of Palestinian security in Gaza, dismissed the 24 withdrawals as cosmetic: "It is talk for television. It has no value on the ground."

The Israeli government indicated yesterday that it envisaged its forces remaining in occupation of West Bank cities and towns such as Ramallah and Bethlehem for weeks, in spite of a call by Mr Powell, backed up by the US president, George Bush, for an immediate withdrawal.

The Israel army said tanks and troops swept into the Palestinian towns of Bir Zeit and Dahariya and the Ein Beit Elma refugee camp, near the city of Nablus, yesterday, making dozens of arrests, seizing arms and occupying buildings.

Israeli security sources said soldiers raided Tulkarm, also on the West Bank, and arrested a woman they accused of planning a suicide bombing, disguising herself as pregnant.

Mr Powell is scheduled to meet Mr Sharon today and the Palestinian leader, Yasser Arafat, tomorrow. Last night Mr Arafat denounced the Israeli siege of the Church of the Nativity in Bethlehem, where Palestinian gunmen are holed up with Franciscan monks.

Speaking to a packed cathedral in Cairo from his cell phone in his Ramallah compound, Mr Arafat said, to loud applause: "The aggression that happened today against the Church of the Nativity ... is a crime ... we will continue to defend these churches regardless of anybody. We will die in defending ourselves."

The Israeli foreign minister, Shimon Peres, in an interview with the US network NBC, confirmed that Israel was not planning a rapid withdrawal: "I do hope that we shall be able to conclude the whole operation within a matter of two weeks or three weeks, maximum."

Mr Powell will try to tie the Israelis down to a much faster timetable. He will also try to negotiate a ceasefire and move as quickly as possible to the next stage of the peace process.

He said his intention was to start "a negotiating process that leads to what the Palestinian people want, a state where they can raise their children and design their own future living side by side with Israel. Everything that is happening now is an impediment to getting to that end point".

On his way from Spain Mr Powell stopped off in Jordan for talks with its leader, King Abdullah, one of the moderate Arab leaders, before continuing to Israel. About 500 Jordanians demonstrated outside the king's palace, shouting "Death to America" and burning the Stars and Stripes.

The White House spokesman, Ari Fleischer, yesterday raised no objection to Israel's failure to respond positively to Mr Bush's demands for Israeli withdrawal more than week ago. "Withdrawals he called for are continuing," Mr Fleischer said, reiterating that Mr Bush also wants Mr Arafat to denounce suicide bombings.